Wheelchairs are convenient for elderly and disabled passengers to travel without the use of their legs. The standard wheelchairs generally include a seat, a frame, an axle, two drive wheels, and two castor wheels. A passenger propels the wheelchair by grabbing a ring on each drive wheel and rolling the wheelchair forward.
A common way to make businesses and homes more accessible to wheelchairs is to install ramps in areas where stairs are present. A problem arises, however, when the wheelchair is disposed on an incline. Due to gravity and the rolling action of the wheelchair, there is a tendency for the wheelchair to roll backwards down the incline. Accordingly, brakes are included on the drive wheels to prevent this motion. This does not, however, aid the passenger attempting to climb an incline as the brakes must be released to allow forward progress of the wheelchair.
Many wheelchair users lack the strength to climb even a moderate incline in one uninterrupted exertion. However, the user cannot rest or the wheelchair will roll rearwardly down the incline. Furthermore, the brakes are almost impossible to use during a climb because if the wheels are released to apply the brakes, the wheelchair will begin rolling rearwardly before the brakes can be actuated. Thus, the wheelchair user would still be dependent on the assistance of others in climbing the incline.
Ratcheting wheelchair wheel assemblies have been created to solve this problem. These assemblies permit rotation of the drive wheels in only one direction. Thus, forward motion of the wheelchair is permitted for a passenger attempting to climb an incline. However, the passenger can rest without fear of losing forward progress because the ratchet assembly will prevent rearward motion of the wheelchair. The passenger may then continue forward progress after resting, and complete climbing the incline.
The current one way wheel assemblies, while effective, are undesirable for many reasons. Primarily, the ratcheting mechanisms are often highly complex and require a separate connection apparatus to interact with the drive wheels. The complexity of the mechanism leads to difficult and labor intensive assembly. Furthermore, these complex systems are costly due to the large number of parts required for construction.
For example, U.S. Pat. No. 4,865,344 to Romero, Sr. et al, issued Sep. 12, 1989, discloses a wheelchair including a ratcheting wheel assembly of this type. The wheelchair includes a drive wheel rotatably disposed on a primary axle. A separate secondary wheel is rotatably disposed on a secondary axle and is connected to the primary wheel via a chain. The movement of the secondary wheel is controlled by the ratcheting assembly, and a control assembly moves the ratcheting assembly into and out of engagement. The ratchet assembly thus directly controls the rotating motion of the secondary wheel, and indirectly controls the motion of the drive wheel.